#include <stdio.h>

void swap(int *p1, int *p2) {
    int temp = *p1;
    *p1 = *p2;
    *p2 = temp;
}

int main() {
    int a = 10, b = 20;
    int *pointer_1 = &a;
    int *pointer_2 = &b;
    printf("Before swap: a = %d, b = %d\n", a, b);
    swap(pointer_1, pointer_2);
    printf("After swap: a = %d, b = %d\n", a, b);
    return 0;
}